What is the purpose of the starter relay (starter solenoid) in a motorcycle's electric starting system?

1. It uses a small current from the handlebar starter switch to close heavy contacts, allowing high current from the battery to flow to the starter motor.
2. It acts as a safety switch that disconnects the ignition if the motorcycle falls over.
3. It converts the battery DC voltage into AC voltage to drive the starter motor.
4. It automatically disengages the starter gear from the flywheel once the engine starts.